fixed lint issue of StringUtils file (#480)

* fixed lint issue of StringUtils file

* Fixed null lint issue

.eslintignore

@@ -279,8 +279,6 @@ src/Utils/NotebookConfigurationUtils.ts
 src/Utils/PricingUtils.test.ts
 src/Utils/QueryUtils.test.ts
 src/Utils/QueryUtils.ts
-src/Utils/StringUtils.test.ts
-src/Utils/StringUtils.ts
 src/applyExplorerBindings.ts
 src/global.d.ts
 src/setupTests.ts

src/Explorer/Controls/CommandButton/CommandButtonComponent.tsx

@@ -1,4 +1,4 @@
-import { StringUtils } from "../../../Utils/StringUtils";
+import * as StringUtils from "../../../Utils/StringUtils";
 import { KeyCodes } from "../../../Common/Constants";
 import * as TelemetryProcessor from "../../../Shared/Telemetry/TelemetryProcessor";
 import { Action, ActionModifiers } from "../../../Shared/Telemetry/TelemetryConstants";

src/Explorer/Controls/Notebook/NotebookTerminalComponent.tsx

@@ -4,7 +4,7 @@
 
 import * as React from "react";
 import * as DataModels from "../../../Contracts/DataModels";
-import { StringUtils } from "../../../Utils/StringUtils";
+import * as StringUtils from "../../../Utils/StringUtils";
 import { userContext } from "../../../UserContext";
 import { TerminalQueryParams } from "../../../Common/Constants";
 import { handleError } from "../../../Common/ErrorHandlingUtils";

src/Explorer/Notebook/NotebookComponent/contents/file/text-file.tsx

@@ -1,4 +1,4 @@
-import { StringUtils } from "../../../../../Utils/StringUtils";
+import * as StringUtils from "../../../../../Utils/StringUtils";
 import { actions, AppState, ContentRef, selectors } from "@nteract/core";
 import { IMonacoProps as MonacoEditorProps } from "@nteract/monaco-editor";
 import * as React from "react";

src/Explorer/Notebook/NotebookContentClient.ts

@@ -1,6 +1,6 @@
 import * as DataModels from "../../Contracts/DataModels";
 import { NotebookContentItem, NotebookContentItemType } from "./NotebookContentItem";
-import { StringUtils } from "../../Utils/StringUtils";
+import * as StringUtils from "../../Utils/StringUtils";
 import { FileSystemUtil } from "./FileSystemUtil";
 import { NotebookUtil } from "./NotebookUtil";
 

src/Explorer/Notebook/NotebookUtil.ts

@@ -1,7 +1,7 @@
 import path from "path";
 import { ImmutableNotebook, ImmutableCodeCell } from "@nteract/commutable";
 import { NotebookContentItem, NotebookContentItemType } from "./NotebookContentItem";
-import { StringUtils } from "../../Utils/StringUtils";
+import * as StringUtils from "../../Utils/StringUtils";
 import * as GitHubUtils from "../../Utils/GitHubUtils";
 
 // Must match rx-jupyter' FileType

src/Utils/StringUtils.test.ts

@@ -1,4 +1,4 @@
-import { StringUtils } from "./StringUtils";
+import * as StringUtils from "./StringUtils";
 
 describe("StringUtils", () => {
   describe("stripSpacesFromString()", () => {
@@ -12,9 +12,9 @@ describe("StringUtils", () => {
       expect(transformedString).toBe("abc");
     });
 
-    it("should return null if input is null", () => {
+    it("should return undefined if input is undefined", () => {
-      const transformedString: string = StringUtils.stripSpacesFromString(null);
+      const transformedString: string = StringUtils.stripSpacesFromString(undefined);
-      expect(transformedString).toBeNull();
+      expect(transformedString).toBeUndefined();
     });
 
     it("should return undefined if input is undefiend", () => {

src/Utils/StringUtils.ts

@@ -1,21 +1,19 @@
-export class StringUtils {
+export function stripSpacesFromString(inputString: string): string {
-  public static stripSpacesFromString(inputString: string): string {
+  if (inputString === undefined || typeof inputString !== "string") {
-    if (inputString == null || typeof inputString !== "string") {
+    return inputString;
-      return inputString;
-    }
-    return inputString.replace(/ /g, "");
-  }
-
-  /**
-   * Implementation of endsWith which works for IE
-   * @param stringToTest
-   * @param suffix
-   */
-  public static endsWith(stringToTest: string, suffix: string): boolean {
-    return stringToTest.indexOf(suffix, stringToTest.length - suffix.length) !== -1;
-  }
-
-  public static startsWith(stringToTest: string, prefix: string): boolean {
-    return stringToTest.indexOf(prefix) === 0;
   }
+  return inputString.replace(/ /g, "");
+}
+
+/**
+ * Implementation of endsWith which works for IE
+ * @param stringToTest
+ * @param suffix
+ */
+export function endsWith(stringToTest: string, suffix: string): boolean {
+  return stringToTest.indexOf(suffix, stringToTest.length - suffix.length) !== -1;
+}
+
+export function startsWith(stringToTest: string, prefix: string): boolean {
+  return stringToTest.indexOf(prefix) === 0;
 }